1. Field of the Invention
The present invention relates to a brazed sintered compact in which two components are brazed to each other, using a brazing material.
2. Description of the Related Art
For conventional art of this kind, it is widely recognized to manufacture a brazed sintered compact in which a first component and a second component are formed by sintering, and then the two components are brazed to each other. Such method has been utilized for manufacturing a product of complex shape, such as planetary carriers for use with an automatic shift for automobiles. Such planetary carriers have been manufactured in the past by subjecting an entire perimeter of cast iron material or a copper plate material to machine processing, resulting to increased man-hours and costs. Therefore, they are now manufactured through the above-mentioned method, i.e., by forming first and second components by sintering green compact and then brazing them to each other.
According to the conventional art, when joining the first and second components to each other by brazing, they are combined together by precise positioning therebetween. In that case, a joining clearance for allowing a brazing material to permeate between the two components becomes a problem.
In other words, if a joining clearance is too large, the penetration amount of the brazing material into the respective components will be too much, so that the components will be expanded and thus distorted, resulting to a likelihood of the noticeable drop of the components' strength. On the other hand, if a joining clearance is too small, there is a risk that the joint strength between the two components drops. Accordingly, it has been a problem how such joining clearance for allowing a brazing material to permeate could be optimized.
Also, whilst Japanese Patent publication No.2000-109907 teaches that small protrusion and recess for guiding purpose are formed on a joining portion so that the former is fitted into the latter in advance, the conventional art had another problem that as a brazing material would be very likely to flow out to the external when the brazing material was placed between the components and heated, such surplus brazing material had to be removed. A solution for solving such problem is proposed by the same applicant in Japanese Patent Application No. 2000-270581 (Publication No.2002-79372). This prior art discloses brazed sintered compact consisting at least of a first component and a second component to be brazed to the first component, in which one of the first and second components has a joining surface formed with a protrusion, while the other thereof has a joining surface formed with a recess, said recess being fitted to said protrusion, having such a depth as allow for a desirable joining clearance with the protrusion being fitted into the recess; and that one of the joining surfaces is formed in a perimeter thereof with a storage groove for storing surplus brazing material, thereby preventing the brazing material from flowing out to the external of the components owing to such groove.
According to the prior art disclosed in the above earlier application, however, the components slightly overhang the groove so that the surplus brazing material is unlikely to be easily discharged, and that the joining clearance could not be optimized duo to the backflow of the brazing material which flowed out to the external and the resultant re-permeation thereby.